Animal husbandry involves controlling the movements of livestock. Driveways often must have a gate to prevent the livestock (such as sheep, goats, pigs or calves) from entering into areas reserved for human use or into gardens. Such gates have typically been made of wood or aluminum. Large, wooden gates are quite heavy and difficult repeatedly to open and close, especially for smaller or less strong persons. Aluminum gates, while lighter in weight, tend to bend, particularly when pushed by livestock, and often have rough edges which pose a hazard to animals and humans.
Similarly in animal husbandry, there is often a need for temporary animal pens for livestock. Wooden structures are usually too heavy to be readily portable.
It has been known to cover wooden or steel building components, such as posts and rails, with sheaths of hollow plastic. For example, U.S. Pat. No. 4,516,756, issued May 14, 1985, inventor Beatty, discloses a fence post encased in a rigid hollow polyvinyl chloride sheath. U.S. Pat. No. 3,554,494, issued Jan. 12, 1971, inventor Bee, discloses a fence structure of hard polyvinyl chloride having its interior divided into a plurality of channels into which is slidingly fit timber or steel. However, these prior known posts and fences are relatively massive, permanent structures and do not solve the need for smooth, lightweight and portable building components.
U.S. Pat. No. 4,477,059, issued Oct. 16, 1984, inventor Willis, discloses a fence formed of hollow fiberglass posts and rails. Although apparently lightweight, the fence is intended to be permanently set by posts into the ground, has no permanent internal reinforcing, and has no means of selectively reinforcing, or making more massive, as may be occasionally needed.